ISSN:
0009-2940
Keywords:
Bipyrroles
;
Tetrapyrroles
;
Tripyrroles
;
Polypyrroles
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The electrochemical and chemical oxidative α,α'-coupling of 3-methoxy-4-methyl-2-pyrrolecarboxylic acid (2) and its ethyl ester 4 is compared with that of the corresponding 4-methoxy-2-pyrrolecarboxylates (1 and 3 respectively). The β-alkoxy substituent exerts a strong directing influence on its vicinal α-position, which in the case of compounds 2 and 4 determines the 2,5'-coupling and allows the isolation of the corresponding 1H,2'H-2,2'-bipyrrole 6 in the case of 4. For 2 the polypyrrole can be obtained by exhaustive electrochemical or chemical coupling, whereas in the case of 1 only the corresponding tetramers are formed. The structures of these tetrapyrroles, already described in the literature, here obtained by oxidation of 4-alkoxy-2-pyrrolecarboxylic acid (1), have been reexamined: they are mixtures of tetramers with zwitterionic structure, have at least two substitution patterns and are partially oxidized to the corresponding bipyrrolylidenes.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19931261017
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